The present invention relates to process and apparatus for spreading a chip web from a supply over a width corresponding to the width of the web on a substrate moving below the supply according to a web height distribution specified in the web transversely to the direction of travel of the web.
European Patent No. 0 063 162 describes a process for influencing the density distribution of a chip web to be spread as well as an apparatus for this purpose. From at least one partial flow over a part of its width according to a specified density distribution, a resulting partial amount is removed. By removing a partial amount from a continuous partial flow extending over the width, a desired density distribution is obtained at the site of removal. However, since a further mixing with uninfluenced partial flows takes place, the desired result of a uniform specified density distribution in the laid down web is difficult to obtain.
Also, European Patent No. 0 109 456, describes process and apparatus for equalizing the density distribution in an artifical wood board in which, as a function of the weight distribution measured over a delivery cross section of the bulk material delivered from a supply, a separation command is developed for the amount of bulk weight present in corresponding partial cross sections and deviating from a specified target density distribution for its separation. Such a process is also based on a supply which is delivered over the entire future web width via removal devices so that density fluctuations present in the supply over the entire width also influence the amount to be removed. Even when the amount to be removed is controlled according to the expected profile which is to be produced on the web substrate, it is entirely possible that as a result of inevitable non-uniformities in the supply, a new non-uniformity in the laydown profile of the chips occurs before laydown as a web. The delivery elements for the stored supply extend over the entire width of the future profile and cause unavoidable defects in the state of the art.
Also, by way of background, German Preliminary Published Application No. 2 942 163 describes process and apparatus for dividing a forwarded flow characterized in that the forward flow is continuously delivered to a flow divider and constant partial flows are forwarded along the flow divider while others are constantly forwarded through the flow divider. With such a process and apparatus, the amount of chips delivered to this flow divider are exactly divided but the defects present in the spreading material are also forwarded via a distribution chute.